Finger bones not moving in line with hand?
To me it looks like your fingzrs are influenced by several bones more than they should be.
Each vertex has an influence vale between zero and one. Bones influencing the same vertex can share the incluence valur, i.e. 0,3 for one and 0,7 for another. The total is always 1.
If a veetex is influenced by several bones and the addotion of the influences is &gt;1, there will be issues.
Go in weight paint mode and make sure nothings wrongly influenced by a bone that shouldn't. Also, you can use the weight normalization tools to help you keep influences ≤1.